In a typical polyethylene plant, a purge gas leaving a purge vessel upon purging a polyethylene polymer product may contain significant amounts of valuable hydrocarbons, including ethylene, isobutane, and comonomers. There are economic and environmental incentives to recover these hydrocarbons from the purge gas. Generally, a selective membrane based separation process or a pressure swing adsorption (PSA) process can be used for the recovery of hydrocarbons from the purge gas. The purge gas coming out of the purge vessel is usually sent through a compressor to increase the separation efficiency downstream of the compressor, whether the separation is done by selective membrane or by PSA. Recycle streams from the separation process can be sent back to the compressor; however, this increases the compressor load, which may limit the amount of purge gas that can be run through the separation process. Thus, there is an ongoing need for developing efficient processes for the recovery of hydrocarbons during polyethylene production.